Harmonic producing apparatus



Feb. 7, 1939.

E. PETERSON 2,145,091 HARMONIC PRODUCING APPARATUS Filed April 9, 1938FIG.

ODD HARMONICS EVEN HARMONICS 42 5 FIG. 2

P F 0 Z FIG. 3 5/ HH l 50 PH 55 M g I T 33 000 [AND EVEN. I y lHARMONICS I'VVE/VTOR E. PE TERSO/V By WM/43,1 1

ATTORNEY Patented Feb. 7, 1939 HARMONIC PRODUCING APPARATUS EugenePeterson, New

York, N. Y., assignor to Bell Telephone Laboratories, Incorporated, NewYork, N. Y., a corporation of New York Application April 9, 1938, SerialNo. 201,052

6 Claims.

This invention relates to harmonic producing apparatus, and moreparticularly to a device for producing both odd and even harmonics.

It is well known that a fundamental frequency 6 of alternating currentcan be distorted in suitable apparatus of magneticor thermionic type toproduce harmonics thereof. In this connection the copending applicationof L. R. Wrathall, Serial No. 77,989, filed May 5, 1936, now Patent No.2,117,752, dated May 17, 1938, discloses a system utilizing a non-linearinductance for producing from a fundamental current a desired range ofodd harmonics having uniformly large amplitudes extending over theentire range. In this system a copper-oxide bridge is employed torectify odd harmonics to obtain even harmonics of the fundamentalcurrent.

It is an object of the invention to provide means for simultaneouslyproducing ranges of odd and even harmonics both of which have uniformlylarge amplitudes extending over the entire ranges.

It is another object of the invention to produce a wave pattern thatincludes fundamental current and a range of harmonics thereof.

It is still another object of the invention to produce a wave patterncomprising fundamental current and odd harmonics thereof both of whichare applied to a single apparatus which amplifies the fundamentalcurrent and effects both odd and even harmonics of the initial oddharmonics.

In one embodiment the invention comprises a source of fundamentalcurrent coupled to a pair of three-element thermionic tubes whose outputcomprises a pair of divided circuits in parallel and a common circuit.One divided output circuit is coupled to a non-linear inductance forapplying amplified fundamental current thereto. The output of thenon-linear inductance comprising a capacity and a resistance in seriesfor producing a series of relatively sharp pulses is coupled to thethermionic tubes so as to superpose the sharp pulses on the fundamentalcurrent. A phase shifting network included in the coupling of thethermionic tubes to the non-linear inductance serves to so shift thephase of the amplified fundamental current'that a wave pattern appliedto the thermionic tubes is-such that the sharp pulses preferably leadthe fundamental current by substantially 90- degrees. The other Theinvention will be more readily understood from the following descriptiontaken together with the accompanying drawing in which:

Fig. 1 is a diagrammatic circuit illustrating one embodiment of theinvention;

Fig. 2 is a wave pattern produced in accordance with the invention andutilized in Figs. 1 and 3; and

Fig. 3 is also a diagrammatic circuit showing an alternate embodiment ofthe invention.

Referring to Fig. 1 a generator H) of alternating current of fundamentalfrequency is connected to the primary of a transformer II Whosesecondary at the opposite ends is applied to divided input circuits l2,l2 including inductances I3 and [4 to the grids of a pair ofthree-element thermionic tubes l6 and i7 having an output comprisingdivided circuits l9, l9 and 20, 20 in parallel and a common circuit 2|.The filaments of the thermionic tubes are preferably heated fromsuitable batteries while the anodes are energized by battery 25.

The potential or biasing battery 26 applied to the grids of thethermionic tubes at the midpoint of the secondary winding of thetransformer H is of such magnitude that the flow of output current isreduced to a relatively low amount during intervals of no gridexcitation voltage. With the arrangement of the secondary winding of thetransformer H, described above, alternating potential supplied by thegenerator 10 is impressed simultaneously on each of the grids but inopposite phase.

The divided output circuit l9, 19 includes inductances 21 and 28together with the primary winding of a transformer 29 Whose secondaryshunted by a condenser 30 is applied through a tuned circuit 32 to anon-linear inductance 33. The output of the latter comprising acondenser 38 and resistance 39 connected in series is coupled bytransformer 40 and condensers 4| and 42 to the grids of the thermionictubes. The nonlinear inductance together with associated input andoutput circuits is disclosed in the copending application of L. R.Wrathall, supra.

The divided output circuit 20, 20 comprises primary windings 43 and 44of a broad band transformer 48 whose secondary winding 45 is appliedacross a work circuit X. Associated with the primary windings 43 and.are the respective blocking condensers 55 and 55 for isolating theamplified fundamental current from the output circuit 20, 20. Themid-point 46 of the primary windings 43 and 44 is connected to thefilaments of the thermionic tubes by means of the common circuit 2|which includes the primary of a transformer 4'! whose secondary windingis applied across a work circuit Y. The work circuits include suitablefilters for selecting harmonics of the fundamental currents produced ina manner that will be subsequently described.

In the operation of the above-explained circuit shown in Fig. l thefundamental current produced in the generator ill is amplified in thethermionic tubes and thereafter applied through the transformer 29 tothe non-linear inductance. As pointed out in the copending applicationof L. R. Wrathall, supra, the output of the nonlinear inductance isproportioned to cause therein the production of a series of sharppulses, one sharp pulse occurring during each half-cycle of thefundamental current. These sharp pulses producing a desired range of oddharmonics having uniformly large amplitudes are then fed back to thetransformer d andcondensers M and d2 through the grids of the thermionictubes to be superposed on the fundamental current. The inductances l 3and M serve to preclude the harmonic energy due to the sharp pulses frompassing into the input circuit l2, l2 while the condensers ii and d2restrict current of the biasing battery 26 to the grid circuits of thethermionic tubes. Due to the arrangement of the thermionic tubes, thedivided output circuit 20, 2!] combines harmonic output energy in adifferential manner so that odd harmonics of the fundamental current aremade available through the work circuit X while thecommon output circuitiicombines harmonic energy in an additive manner to make available tothe work circuit Y even harmonics of the fundamental current.

In accordance with this invention a phase shifting network 3| isconnected in the input of the 'nonlinear inductance, that is, betweenthe secondary winding of the transformer 29 and tuned circuit 32. Theconstants of this phase shifting network are so proportioned that theamplified fundamental current impressed on the non-linear inductance isshifted 90 degrees. This causes a corresponding phase shift of the sharppulses superposed on the fundamental current. Consequently the sharppulses may be leading or lagging the fundamental current by 90 degrees.

In the present case, it is prefered for the efficient operation of thesystem that the constants .'0f the phase shifting network beproportioned so that the sharp pulses lead the fundamental currentby-substantially 90 degrees when both are simultaneously applied to thethermionic tubes.

A wave pattern of this type is shown in Fig. 2 in which it is seen thatthe peaks of the sharp pulses P and fundamental current F aresubstantially of the same magnitude and sign although occurring atdifferent time intervals. As previously mentioned, the output of thethermionic tubes is arranged to effect therein both odd and evenharmonies from the odd harmonics due to the sharp pulses while at .thesame time passing amplified fundamental current to the non-linearinductance for the purpose of producing these sharp pulses.Consequently, a single thermionic device is utilized both for amplifyingthe fundamental current anddistorting harmonics thereof. The inductances21 and 28 serve to prevent harmonic energy from passing into the primaryof the coupling transformer 29.

Fig. Bis similar to Fig. 1, except the output circuit 50 of-thenon-linear inductance 33 is connected through leads 5l-to the mid-pointof the the potentials of the fundamental and harmonic currents aresimultaneously applied to the grids of the thermionic tubes but inopposite phase. In other words, the fundamental and harmonic currentsare differentially applied to the thermionic tubes. In addition, biasingbattery 52 impressed on the filaments of the thermionic tubes is of suchmagnitude that the flow of output current is reduced to a relativelysmall amount with no grid excitation voltage, and inductances l3 and idin the amplifier input i2, 12 (Fig. 1) together with the inductances 2!and. 28 in the divided output l9, 19 (Fig. l) are omitted.

In Fig. 3 the constants of the phase shifting network are soproportioned that the wave pattern applied to the grids of thethermionic tubes is identical with that shown in Fig. 2. In this case,however, both odd and even harmonics of the fundamental current aresupplied to a work circuit X, Y connected across the secondary windingof a transformer .53 whose primary winding is connected in thefilament-plate circuits of the thermionic tubes. The work circuitincludes suitable filters for selecting the odd and even harmonics.

While the invention is particularly described with reference to acircuit utilizing a non-linear inductance for producing sharply peakedwaves, it is not necessarily limited thereto as it is equally applicableto a circuit employing any suitable means for producing sharply peakedwaves. In this connection, such means would, for example, includegaseous discharge devices,thyrite, copperoxide, each having a non-linearcharacteristic. Consequently, it is understood that the invention iscapable of modifications other than those disclosed herein, and thescope thereof together with such modifications is defined in theappended claims.

What is claimed is:

1. In a harmonic producing system including a source of fundamentalcurrent, an amplifying and distorting device having an input and anoutput. means for coupling the fundamental source to the input of theamplifying and distorting device, a non-linear device, means forcoupling the output of the amplifying and distorting device to thenon-linear device for impressing amplified fundamental current thereon,an output circuit for the non-linear device including a condenser andresistance in series both of which are proportioned to produce a seriesof relatively sharp pulses and thereby odd harmonics of the fundamentalcurrent, means for connecting the output of the nonlinear device to theamplifying and distorting device'to superpose the sharp pulses on thefundamental. current, means included in the output of the amplifying anddistorting means for effecting therein odd and even harmonics of thefundamental current, means consisting of a phase shifting network for soadjusting the phaseof the amplified fundamental current applied to thenon-linear inductance that the wave pattern impressed-on the amplifyingand distorting device comprises sharp pulses and fundamental currentboth of which have peaks of substantially the same magnitude and of thesame sign.

2. In a harmonic producing system'including a source of fundamentalcurrent, an amplifying and distorting device having an input and anoutput,

means for coupling the source to the input of the plifying anddistorting-device to the non-linear device for applying'amplifledfundamental current thereto, an output circuit for the non-linear deviceincluding a condenser and a resistance series both of which areproportioned to produce a series of relatively sharp pulses and therebyodd harmonics of the fundamental current, means for coupling the outputof the non-linear device to the amplifying and distorting device tosuperpos-e -the sharp pulses on the fundamental current, work circuits,means included in the output of the amplifying and distorting device todifferentially and additively connect the work circuits theretoforrespectively producing therein odd and even harmonics of thefundamental current, means comprising a phase shifting apparatus for soadjusting the phase of the fundamental current that the peaks of thesharp pulses and fundamental current applied to the amplifying anddistorting device occur at'diiferent time intervals.

3. The harmonic producing system according to claim 2 in which theconstants of the phase shift: ing apparatus are so proportioned that thepeaks of the sharp pulses and fundamental current are of the same sign.

4. The harmonic producing system according to claim 2 in which theconstants of the phase shifting apparatus are so proportioned that thepeaks of the sharp pulses and fundamental current are of the same signand of substantially the same magnitude.

5. The harmonic producing system according to claim 2 in which theconstants of the phase shifting apparatus are so proportioned that thephase of the amplified fundamental current is shifted degrees.

6. In a harmonic producing system including a source of fundamentalcurrent, an amplifying and distorting device, means for differentiallyconnecting the fundamental source to the amplifying and distortingdevice, a non-linear device, means for coupling the output of theamplifying and distorting device to the non-linear device for applyingamplified fundamental current thereto, an output circuit for thenon-linear device including a condenser and resistance in series both ofwhich are proportioned to produce a series of relativeli sharp pulsesand thereby a range of odd harmonics of the fundamental current, meansfor connecting the output circuit of the non-linear device to thedifferentially connected means for superposing sharp pulses on thefundamental current, a work circuit, means included in the output of theamplifying and distorting device for supplying to the work circuitodd'and even harmonics of the fundamental current, means comprising aphase shifting network for so adjusting the phase of the amplifiedfundamental current applied to the non-linear inductance that the wavepattern applied to the amplifying and distorting device consists ofsharp pulses and fundamental current whose peaks are of the same sign,substantially of equal magnitude and occur at different time intervals.v

EUGENE PETERSON.

